The migration requirements are impossible given the current state of the database
You probably can’t join two distinct clusters without app changes and without downtime unless you’re very lucky (same cluster name, app using quorum but not local quorum, both clusters using NetworkTopologyStrategy, neither app using serial reads or writes), and trying to do it with conflicting keyspace and table names makes it impossible Would just assume this isn’t possible and look for alternate plans, like downtime or code changes. > On Jan 17, 2020, at 6:40 AM, Durity, Sean R <sean_r_dur...@homedepot.com> > wrote: > > > A couple things to consider: > A separation of apps into their own clusters is typically a better model to > avoid later entanglements > Dsbulk (1.4.1) is now available for only open source clusters. It is a great > tool for unloading/loading > What data problem are you trying to solve with Cassandra and this move to > another cluster? If it is high-availability, then trying to get to 2 DCs > would be important. However, I think you will need at least a new keyspace if > you can’t combine the data from the clusters. Whether this requires a code or > config change depends on how configurable the developers made the connection > and query details. (As a side rant: why is it that developers will write all > kinds of new code, but don’t want to touch existing code?) > Your migration requirements are quite stringent (“we don’t want to change > anything, lose anything, or stop anything. Make it happen!”). There may be a > solution, but you may end up with something even more fragile afterwards. I > would push back to see what is negotiable. > > > > Sean Durity – Staff Systems Engineer, Cassandra > > From: Ankit Gadhiya <ankitgadh...@gmail.com> > Sent: Friday, January 17, 2020 8:50 AM > To: user@cassandra.apache.org > Subject: [EXTERNAL] Re: *URGENT* Migration across different Cassandra cluster > few having same keyspace/table names > > Hi Upasana, > > Thanks for your response. I’d love to do that as a first strategy but since > they are both separate clusters , how would I do that? Keyspaces already have > networktopologystrategy with RF=3. > > > — Ankit > > On Fri, Jan 17, 2020 at 8:45 AM Upasana Sharma <028upasana...@gmail.com> > wrote: > Hi, > > Did you consider adding Cassandra nodes from cluster B, into cluster A as a > different data center ? > > Your keyspace would than be on Network topology data strategy. > > In this case, all data can be synced between both data centers by Cassandra > using rebalancing. > > > At client/application level you will have to ensure local quorum/ local > consistency so that there is no impact on latencies. > > Once you have moved data applications to new cluster , you can then remove > the old data center (cluster A), and cluster B would have fresh data. > > > > > On Fri, Jan 17, 2020, 6:59 PM Ankit Gadhiya <ankitgadh...@gmail.com> wrote: > Thanks but there’s no DSE License. > Wondering how sstableloader will help as some oh the Keyspace and tables > names are same. Also how do i sync few system keyspaces. > > > Thanks & Regards, > Ankit > > On Fri, Jan 17, 2020 at 1:11 AM Vova Shelgunov <vvs...@gmail.com> wrote: > Loader* > > https://www.datastax.com/blog/2018/05/introducing-datastax-bulk-loader > [datastax.com] > > On Fri, Jan 17, 2020, 09:09 Vova Shelgunov <vvs...@gmail.com> wrote: > DataStax bulk loaded can be an option if data is large. > > On Fri, Jan 17, 2020, 07:33 Nitan Kainth <nitankai...@gmail.com> wrote: > If the keyspace already exist, use copy command or sstableloader to merge > data. If data volume it too big, consider spark or a custom java program > > > Regards, > Nitan > Cell: 510 449 9629 > > > On Jan 16, 2020, at 10:26 PM, Ankit Gadhiya <ankitgadh...@gmail.com> wrote: > > > Any leads on this ? > > — Ankit > > On Thu, Jan 16, 2020 at 8:51 PM Ankit Gadhiya <ankitgadh...@gmail.com> wrote: > Hi Arvinder, > > Thanks for your response. > > Yes - Cluster B already has some data. Tables/KS names are identical ; for > data - I still haven't got the clarity if it has identical data or no - I am > assuming no since it's for different customers but need the confirmation. > > Thanks & Regards, > Ankit Gadhiya > > > > On Thu, Jan 16, 2020 at 8:49 PM Arvinder Dhillon <dhillona...@gmail.com> > wrote: > So as I understand, Cluster B already has some data and not an empty cluster. > > When you say, clusters share same keyspace and table names, do you mean both > clusters have identical data on those ks/tables? > > > -Arvi > > On Thu, Jan 16, 2020, 5:27 PM Ankit Gadhiya <ankitgadh...@gmail.com> wrote: > Hello Group, > > I have a requirement in one of the production systems where I need to be able > to migrate entire dataset from Cluster A (Azure Region A) to Cluster B (Azure > Region B). > > Each cluster have 3 Cassandra nodes (RF=3) running used by different > applications. Few of the applications are common is Cluster A and Cluster B > thereby sharing same keyspace/table names. > Need suggestion for the best possible migration strategy here considering - > 1. No Application code changes possible - Minor config/infra changes can be > considered. 2. Zero data loss. 3. No/Minimal downtime. > > It'd be great to hear ideas from all of you based on your experiences. > > Cassandra Version - Cassandra 3.0.13 on both sides. > Total Data size - Cluster A: 70 GB, Cluster B: 15 GB > > Thanks & Regards, > Ankit Gadhiya > > -- > Thanks & Regards, > Ankit Gadhiya > > -- > Thanks & Regards, > Ankit Gadhiya > > -- > Thanks & Regards, > Ankit Gadhiya > > > > The information in this Internet Email is confidential and may be legally > privileged. It is intended solely for the addressee. Access to this Email by > anyone else is unauthorized. If you are not the intended recipient, any > disclosure, copying, distribution or any action taken or omitted to be taken > in reliance on it, is prohibited and may be unlawful. When addressed to our > clients any opinions or advice contained in this Email are subject to the > terms and conditions expressed in any applicable governing The Home Depot > terms of business or client engagement letter. The Home Depot disclaims all > responsibility and liability for the accuracy and content of this attachment > and for any damages or losses arising from any inaccuracies, errors, viruses, > e.g., worms, trojan horses, etc., or other items of a destructive nature, > which may be contained in this attachment and shall not be liable for direct, > indirect, consequential or special damages in connection with this e-mail > message or its attachment.
